Addition and Subtraction Practice Test

Identify the property of addition demonstrated by the following statement:

Forty-two friends are renting a party bus to the school prom. Rental of the party bus will cost $320 up front plus $18 per hour. The friends have the bus from 5:00 PM to 3:00 AM.

Each friend has agreed to chip in $9. One of the teachers at the high school, Mr. Smith, has offered to chip in the rest. If he does, how much will he pay?